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Item does not contain fulltext Flow-mediated dilation (FMD) is a noninvasive indicator of endothelial function and is routinely expressed as the percentage change in arterial diameter (FMD%) from a resting baseline (Dbase) to a postischemic peak (Dpeak). This expression is equivalent to the ratio of Dpeak/Dbase and is, therefore, dependent on important statistical assumptions, which have never been analysed in the context of FMD%. We aimed to investigate these assumptions, via a comparison of FMD between samples of children and adults, as well as to explore other approaches to scaling diameter change for Dbase. We found that FMD% did not scale accurately for interindividual differences in Dbase but, as expected, overestimated endothelial function for low Dbase and vice versa. We argue that this imprecise scaling of FMD% is predictable, not explained by physiology and is probably common. This problem is resolved by applying scaling principles, whereby the difference in diameter is the outcome and Dbase is a covariate in a logarithmic-linked generalized linear model. A specific allometric expression of FMD can be derived and we found this to be Dpeak/Dbase rather than a simple ratio in our particular dataset. We found that sample differences in endothelial function were inaccurate with FMD% versus our new allometric approach, and that FMD% misclassified participants into 'high' and 'low'cohorts, which has implications for prognostic-type studies. We conclude that the general use of FMD% could have led to biased comparisons of different conditions and/or populations in past studies. Our new approach to scaling FMD is flexible for different datasets and is not based on the current assumption that a percentage change is appropriate in all circumstances.

Item does not contain fulltext PURPOSE: Studies performed in animals and humans strongly suggest that exercise training and physical activity enhance arterial endothelial function. Studies of athletes have, however, been less definitive. METHODS: We recruited a range of Olympic and world class athletes who participate in upper or lower limb predominant activities and examined brachial and superficial femoral artery diameter responses to 5-min ischemia (flow-mediated dilation [FMD]) and glyceryl trinitrate, wall thickness (WT) and wall-to-lumen ratio using Doppler and two-dimensional ultrasound. Subjects were elite male canoe paddlers (n = 12), squash players (n = 13), lower limb dominant athletes (i.e., runners/cyclists/triathletes, n = 13), or age- and sex-matched control subjects (n = 16). RESULTS: Athletes demonstrated lower superficial femoral artery FMD than controls (P < 0.05), whereas in the brachial artery, a lower FMD was found in squash players (P < 0.05). Both arteries showed a significant inverse correlation between diameter and FMD (P < 0.05), and a significant inverse relationship was apparent between wall-to-lumen ratio and FMD in the superficial femoral artery (P < 0.05). CONCLUSIONS: Although artery FMD was lower in athletes, artery size was larger and WT smaller than controls. The apparent reduction in artery FMD may relate to the profound structural remodeling in the diameter and WT of the conduit arteries of athletes. These findings have implications for the interpretation of FMD data, particularly as it pertains to the effect of athletic endeavor on cardiovascular health.

Contains fulltext : 118162.pdf (Publisher’s version ) (Closed access) OBJECTIVE: Formerly preeclamptic women are at increased risk for remote cardiovascular and thrombotic diseases. We studied co-occurrence of cardiovascular and prothrombotic risk factors within a cohort of formerly preeclamptic women and tested if prevalence of these risk profiles related to onset of preeclampsia in previous pregnancy. METHODS: We evaluated 1,297 nonpregnant formerly preeclamptic women (6-12 months postpartum) for the presence of four risk profiles: circulatory risk profile (hypertension or latent hypertension [low plasma volume, increased vascular resistance, or both]; metabolic syndrome (World Health Organization criteria); thrombophilia (factor V Leiden, prothrombin mutation, or protein C or S deficiency); and hyperhomocysteinemia. Trends between prevalence of these four profiles and onset of preeclampsia were studied using linear regression analysis. RESULTS: After exclusion of 63 women (4.9%) because of incomplete data, 1,234 women were included. One or more risk profiles were detected in 958 of 1,234 (77.6%) formerly preeclamptic women. Circulatory risk profile was more prevalent (66.1%) than hyperhomocysteinemia (18.7%), metabolic syndrome (15.4%), or thrombophilia (10.8%). Prevalence of circulatory risk profile, metabolic syndrome, and hyperhomocysteinemia decreased significantly with gestational age at delivery, whereas thrombophilia did not (P=.22). There was minimal overlap (less than 2%) between metabolic syndrome, thrombophilic profile, and hyperhomocysteinemia. CONCLUSION: Circulatory risk profile is present in two thirds of formerly preeclamptic women. Metabolic syndrome, thrombophilia, and hyperhomocysteinemia are prevalent in 10-20%. There is considerable overlap between circulatory risk profile and other profiles, but not among the three other profiles. Prevalence of these risk factors, except thrombophilia, decreases with gestational age at delivery in preceding pregnancy. LEVEL OF EVIDENCE: : II.

Item does not contain fulltext Previous studies have demonstrated conflicting results on the effects of acute exercise on FMD. The aim of the study was to examine brachial artery FMD before and after 3 bouts of acute exercise performed at different intensities. 10 healthy males (mean+/-SD age: 22+/-1 years) completed 30 min of cycling at 50, 70 and 85% maximal heart rate (HRmax). Brachial artery FMD and the shear rate area-under-the-curve (cuff deflation to peak dilation; SRAUC) were assessed pre- and immediately post-exercise using high-resolution echo-Doppler. A generalized estimating equation (GEE) analysis was used to estimate the effect magnitudes of exercise intensity and time (pre/post) on FMD, whilst controlling for the influence of baseline diameter and SRAUC. Both baseline diameter and SRAUC were elevated by exercise. With covariate-control of these variables, the decrease in brachial artery FMD was negligible after exercise at 50% HRmax (6.3+/-2.6 vs. 5.9+/-2.5%; 95%CI for difference: - 0.59-1.34%) with larger decreases in FMD after exercise at 70% (6.1+/-1.8 vs. 4.7+/-1.9%; 95%CI for difference: 0.08-2.58%) and at 85% HRmax (6.6+/-1.6 vs. 3.6+/-2.2%; 95%CI: 0.41-5.42%). In conclusion, even after accounting for exercise-mediated changes in shear and baseline diameter, our data indicate that a negative relationship exists between exercise intensity and FMD. 01 mei 2013

Item does not contain fulltext Exercise training is associated with direct effects on conduit artery function and structure. Cross-sectional studies suggest the presence of systemic changes in wall thickness as a result of exercise in healthy subjects, but no previous study has examined this question in humans undertaking exercise training. OBJECTIVE: To examine the change in superficial femoral (SFA, i.e. local effect) and carotid (CA, i.e. systemic effect) artery wall thickness across 8 weeks of lower limb cycle training in healthy young men. METHODS: Fourteen healthy young male subjects were assigned to an 8-week training study of cycling exercise (n = 9) or a control period (n = 5). Before, during (2, 4 and 6 weeks) and after training, SFA and CA wall thickness was examined using automated edge-detection of high resolution ultrasound images. We also measured resting diameter and calculated the wall:lumen(W:L)-ratio. RESULTS: Exercise training did not alter CA or SFA baseline diameter (P = 0.14), but was associated with gradual, consistent and significant decreases in wall thickness and W:L-ratio in both the CA and SFA (P < 0.001 and 0.002, respectively). Two-way ANOVA revealed a comparable magnitude of decrease in wall thickness and W:L-ratio in both arteries across the 8-week period (interaction-effect; P = 0.29 and 0.12, respectively). No changes in artery diameter, wall thickness or W:L-ratio were apparent in controls (0.82, 0.38 and 0.52, respectively). CONCLUSION: We found that cycle exercise training in healthy young individuals is associated with modest, but significant, decreases in wall thickness in the superficial femoral and carotid arteries. These findings suggest that exercise training causes systemic adaptation of the arterial wall in healthy young subjects. 01 augustus 2013

The impact of manipulating shear stress on conduit artery vasodilation has not been comprehensively described in vivo. We hypothesized that manipulation of SR through the brachial and radial arteries would be associated with corresponding changes in diameter. We performed a series of studies involving the following: (1) leg cycle exercise at increasing intensities (≈70 and 85% maximum heart rate [HRmax]) with simultaneous bilateral measurement of SR in the radial arteries; (2) leg cycle exercise for 30 minutes at 80% HRmax with simultaneous bilateral measurement of velocity and diameter in the brachial arteries; and (3) bilateral forearm heating for 30 minutes with simultaneous bilateral measurement of brachial artery diameter and blood velocity. Cycling and forearm heating interventions were performed in the presence of unilateral cuff inflation throughout the experiment, or starting during the intervention (15 minutes), to manipulate SR responses. Cuff placement was associated with lower radial artery SR responses (cuffed versus uncuffed, 248±49 versus 349±105 L/s 85% HRmax; P P P P P

Item does not contain fulltext Maintaining a proper fluid balance is important during exercise as athletes are prone to develop dehydration during exercise. Although several factors may regulate the fluid balance, little is known about the role of sex during prolonged moderate-intensity exercise. Therefore, we compared body mass changes and fluid balance parameters in men vs women in a large heterogeneous group of participants during prolonged exercise. Ninety-eight volunteers walked 30-50 km at a self-selected pace. Exercise duration (8 h, 32 min) and intensity (69% HRmax ) were comparable between groups. Men demonstrated a significantly larger change in body mass than women (-1.6% vs -0.9%, respectively, P < 0.001) and a higher incidence of dehydration (defined as >/=2% body mass loss) compared with women (34% vs 12%, respectively, odds ratio = 4.2, 95% CI = 1.1-16.7). Changes in blood sodium levels were significantly different between men (+1.5 mmol/L) and women (-0.4 mmol/L), while 27% of the men vs 0% of the women showed postexercise hypernatremia (sodium levels >/= 145 mmol/L). Moreover, men demonstrated a significantly lower fluid intake (2.9 mL/kg/h) and higher fluid loss (5.0 mL/kg/h) compared with women (3.7 and 4.8 mL/kg/h, respectively). Taken together, our data suggest that men and women demonstrate different changes in fluid balance in response to a similar bout of exercise.

Item does not contain fulltext Exercise training is associated with rapid changes in endothelium-dependent vasodilation, which occur within days of training. Whilst long-term physical inactivity has potent effects on vascular structure, little is known about the immediate impact of inactivity on vascular function. Aim of this study was to measure vascular function before, during (day 4) and after 8 days of unilateral forearm inactivity. Thirteen healthy male subjects (22 +/- 1 years) were instructed to wear a sling on the non-dominant arm to induce local inactivity. Before, during (at 4 days) and after the 8-day intervention, we used echo Doppler to measure bilateral brachial artery dilator response to 5-min ischaemia [i.e. flow-mediated dilation (FMD)], ischaemic handgrip exercise (iEX) and endothelium-independent dilation to a NO donor [i.e. glyceryl trinitrate (GTN)]. Maximal handgrip strength of the inactive forearm significantly decreased after 8 days (t tests P = 0.03 for Day 0 vs. Day 8), confirming physical deconditioning in the inactive forearm. A significant decrease in peak blood flow was found in the intervention arm (sling: 539 +/- 236, 528 +/- 184, 384 +/- 142 ml/min) relative to the control arm (559 +/- 181, 591 +/- 219, 613 +/- 169 ml/min; 2-way ANOVA interaction: P = 0.05). Analysis revealed no significant change in brachial artery baseline diameter, FMD %, iEX or GTN across the 8 days in either arm (P > 0.05). Eight days of forearm physical inactivity induced a significant decrease in post-ischaemic limb blood flow, suggestive of remodelling of forearm resistance vessels. However, measures of conduit artery endothelium-dependent vasodilation were not altered across an 8-day period of inactivity, suggesting that initial remodelling occurs at distal ends of the vascular tree.

Item does not contain fulltext PURPOSE: Patients suffering from postcancer fatigue have both an inferior physical activity and physical fitness compared to non-fatigued cancer survivors. The aims of this study were (1) to examine the effect of cognitive behavior therapy, an effective treatment for postcancer fatigue, on physical activity and physical fitness and (2) to examine whether the effect of cognitive behavior therapy on postcancer fatigue is mediated by physical activity and/or physical fitness. METHODS: Severely fatigued cancer survivors were randomly assigned to either the intervention (cognitive behavior therapy) or the waiting list condition. After assigning 23 patients in the intervention condition and 14 patients in the waiting list condition, they were assessed both at baseline and 6 months later. Physical activity was assessed via actigraphy and physical fitness was assessed by a maximal exercise test. A nonparametric bootstrap approach was used to test the statistical significance of the mediation effects. RESULTS: A significant increase in physical activity was observed in the intervention group from baseline to follow-up, whereas physical activity did not change from baseline to follow-up in the waiting list group. Physical fitness did not significantly change after cognitive behavior therapy or after 6 months of waiting for therapy. Fatigue decreased more significantly in the intervention group than in the waiting list group. The mediation hypotheses were rejected. CONCLUSIONS: Cognitive behavior therapy effectively reduced postcancer fatigue and increased physical activity but did not change physical fitness. The effect of cognitive behavior therapy on postcancer fatigue is not mediated by a change in physical activity or physical fitness.

Contains fulltext : 117799.pdf (Publisher’s version ) (Closed access) Physical inactivity and exercise training result in opposite adaptations of vascular structure. However, the molecular mechanisms behind these adaptations are not completely understood. We used a unique study design to examine both vascular characteristics of the superficial femoral artery (using ultrasound) and gene expression levels (from a muscle biopsy) in human models for physical deconditioning and exercise training. Initially, we compared able-bodied control subjects (n = 6) with spinal cord-injured individuals (n = 8) to assess the effects of long-term deconditioning. Subsequently, able-bodied control subjects underwent short-term lower limb deconditioning using 3 weeks of unilateral limb suspension. Spinal cord-injured individuals were examined before and after 6 weeks of functional electrical stimulation exercise training. Baseline femoral artery diameter and hyperaemic flow were lower after short- and long-term deconditioning and higher after exercise training, whilst intima-media thickness/lumen ratio was increased with short- and long-term deconditioning and decreased with exercise training. Regarding gene expression levels of vasculature-related genes, we found that groups of genes including the vascular endothelial growth factor pathway, transforming growth factor beta1 and extracellular matrix proteins were strongly associated with vascular adaptations in humans. This approach resulted in the identification of important genes that may be involved in vascular adaptations after physical deconditioning and exercise.

Item does not contain fulltext PURPOSE: The aim of this study is to examine whether physical fitness of severely fatigued and non-fatigued cancer survivors, as measured by maximal exercise performance, is different between both groups and, if so, whether this difference can be explained by differences in physical activity, self-efficacy regarding the exercise test, and/or social support. METHODS: Severely fatigued (n = 20) and sex- and age-matched non-fatigued (n = 20) disease-free cancer survivors, who completed treatment for a malignant, solid tumor at least 1 year earlier, participated in this case-control study. Maximal oxygen consumption was measured during an incremental cycling exercise test. Physical activity was assessed via actigraphy. Self-efficacy regarding the test and social support were assessed via questionnaires to study its relationship with physical fitness. RESULTS: Maximal oxygen consumption was significantly lower in fatigued compared to non-fatigued participants. Actual physical activity, self-efficacy regarding the test, and negative interactions of social support were significantly different between both groups. However, after inclusion of these three variables in linear regression analyses, the difference in physical fitness between fatigued and non-fatigued cancer survivors persisted. CONCLUSIONS: Maximal oxygen consumption, a measure for physical fitness, was reduced in severely fatigued compared to non-fatigued cancer survivors. The inferior maximal exercise performance cannot fully be explained by differences in physical activity, self-efficacy, or social support between both groups. Other currently still unknown factors, such as a disturbance in the cardiopulmonary circuit, may play a role.

Contains fulltext : 110097.pdf (Publisher’s version ) (Closed access) BACKGROUND More than half of recurrent pregnancy loss (RPL) remains unexplained. We hypothesized that women with a history of unexplained RPL (URPL) have low venous reserve. METHODS Case-control study in 12 women with a history of URPL, 11 healthy nulliparous controls and 12 primiparous controls with a history of uncomplicated pregnancy. To quantify venous reserve, we measured plasma volume (PV, ml/m(2)) and venous compliance in forearm and calf (VC(arm), VC(calf), (ml/dl)/mmHg) during the follicular phase of the menstrual cycle. Mean arterial blood pressure (mmHg) was measured by oscillometry. Arterial demand was evaluated by cardiac index (CI, (l/min)/m(2)). RESULTS Baseline characteristics were comparable between groups. All groups had similar CI. Women with a history of RPL had 14% and 9% lower mean PV compared with nulliparous and primiparous controls (P < 0.01 and P = 0.04, respectively). In women with URPL, the mean VC(arm) was 25% and 32% lower compared with nulliparous and primiparous controls (P = 0.04 and P < 0.01, respectively), while the mean VC(calf) was 29 and 22% lower compared with the two control groups (P < 0.01 and P = 0.03, respectively). CONCLUSIONS Women with URPL have lower venous reserves when compared with controls at comparable arterial demand. Interventions that increase venous reserve may improve pregnancy outcome. 01 september 2012

Item does not contain fulltext STUDY DESIGN: Case-control study. OBJECTIVES: To investigate whether oxygen consumption and blood flow at rest and after exercise are lower in the affected arm of patients with repetitive strain injury (RSI) compared to controls, and lower in the healthy nonaffected forearm within patients with unilateral RSI. BACKGROUND: RSI is considered an upper extremity overuse injury. Despite the local presentation of complaints, RSI may be represented by systemic adaptations. Insight into the pathophysiology of RSI is important to better understand the development of RSI complaints and to develop effective treatment and prevention strategies. METHODS: Twenty patients with unilateral RSI and 20 gender-matched control subjects participated in this study. Forearm muscle blood flow and oxygen consumption were measured using near-infrared spectroscopy at baseline and immediately after isometric handgrip exercises at 10%, 20%, and 40% of the individual maximal voluntary contraction. RESULTS: Unilateral RSI resulted in a lower oxygen consumption and blood flow in the affected forearm at baseline and lower oxygen consumption after incremental handgrip exercises compared to controls (P

Item does not contain fulltext BACKGROUND: The purpose of this study was to evaluate oxygen extraction and utilization in end stage chronic complex regional pain syndrome type I (CRPS I) patients undergoing amputation and to relate these to muscle histology of the amputated limb. MATERIALS AND METHODS: In 25 patients with severe CRPS I requiring amputation of the affected limb venous blood samples and in 11 patients skeletal muscle specimens were analyzed. RESULTS: The mean venous oxygen saturation (S(v)O(2)) value (94.3% +/- 4.0%) of the affected limb was significantly higher than S(v)O(2) values found in healthy subjects (77.5% +/- 9.8%) pointing to a severely decreased oxygen diffusion or utilization within the affected limb. Histologic analysis showed a significant decrease of type I fibers and a significant increase of type IIB fibers. Ultrastructural investigations of soleus skeletal muscle capillaries revealed thickened endothelial cells and thickened basement membranes. Muscle capillary densities were decreased in comparison with literature data. High venous oxygen saturation levels were partially explained by impaired diffusion of oxygen due to thickened basement membrane and decreased capillary density. CONCLUSION: This study shows that venous oxygen saturation is significantly increased in chronic end stage CRPS I patients corresponding with impaired oxygen diffusion. The abnormal skeletal muscle findings points to severe disuse but only partially explain the impaired diffusion of oxygen; mitochondrial dysfunction seems a likely explanation in addition. 01 maart 2012

Item does not contain fulltext BACKGROUND: Hypertrophic cardiomyopathy (HCM) is characterised by idiopathic cardiac enlargement and represents the most frequent cause of sudden cardiac death in athletes under the age of 35 years. Differentiation between physiological (ie, exercise-related) and pathological (ie, HCM-related) cardiac remodelling is challenging. In line with cardiac remodelling, vascular structure and function are altered following training, but little is known about peripheral vascular adaptations in HCM. We hypothesised that, while HCM patients and athletes would exhibit similar cardiac characteristics, differences would be apparent in their brachial and carotid arteries. METHODS: In age-matched groups of HCM patients (n = 18, 39 +/- 15 years), highly competitive athletes (n = 18, 38 +/- 12 years) and recreational controls (n = 10, 37 +/- 14 years), we used high-resolution ultrasound to assess the diameter and wall thickness of the carotid and brachial arteries, with flow-mediated dilator function (FMD) of the brachial arteries also assessed. RESULTS: A significant difference between athletes and HCM was evident in arterial wall thickness (carotid 519 +/- 60 vs 586 +/- 102 microm, p

Item does not contain fulltext BACKGROUND: Rib cage mobility decreases in various health conditions, for example neuromuscular diseases. A decrease in rib cage mobility reduces respiratory function and therefore increases the risk of respiratory complications. To evaluate the effects of interventions aiming at increasing rib cage mobility, changes should be calculated from measurements before and after such interventions. Therefore, an accurate and easy to perform method is needed. OBJECTIVE: To assess rib cage mobility using computed tomography (CT). METHODS: We analysed single-image CT scans of the chest to assess its reproducibility at maximal inspiration and expiration in ten able-bodied individuals and ten subjects with tetraplegia. CT scans were taken twice in the supine position, with a repositioning of subjects in-between. At maximal inspiration and expiration, two images at the fourth and ninth vertebral body were recorded. Intra-costal areas, anterior-posterior distances from the sternum to the vertebral body as well as transversal distances of the chest were measured manually by three independent testers, each of them analysing all data twice. Intra-class correlation coefficients (ICCs) and Bland and Altman plots were calculated for intra-subject reproducibility at maximal inspiration and expiration as well as for intra- and inter-tester reproducibility. RESULTS: Mean differences between the two intra-subject measurements expressed as percentage of their mean were 2.3 +/- 1.3% in able-bodied individuals and 2.1 +/- 1.3% in subjects with tetraplegia. All ICCs were above 0.95 and thus showed very high reproducibility. CONCLUSION: Assessing rib cage mobility by analysing CT scans of the chest is a simple and highly reproducible method. 01 juli 2012

Item does not contain fulltext BACKGROUND: Patients with Parkinson's disease (PD) are physically less active than controls, and autonomic dysfunction may contribute to this sedentary lifestyle. Specifically, an altered cardiovascular response to physical effort may restrict physical activities. OBJECTIVE: To assess the cardiovascular responses to a submaximal exercise test in PD patients and controls, 546 sedentary PD patients and 29 sedentary healthy controls performed the Astrand-Rhyming submaximal cycle exercise test. METHODS: Average heart rate was used to estimate maximal oxygen consumption (VO2max). Variables that may affect submaximal activity in PD patients, including disease severity, fatigue, and level of physical activity in daily life, were recorded. RESULTS: Fewer PD patients (46%) completed the submaximal exercise test successfully than the controls (86%). The estimated VO2max of patients with a successful test was 34% lower than the controls (p < 0.001). Multivariate regression analyses revealed that higher body weight, lower systolic blood pressure, lower resting heart rate, and lower maximal workload were associated with an increased risk of an inadequate heart rate increase during submaximal exercise (R2 = 27%). PD patients with a successful submaximal exercise test had lower estimated VO2max values than controls. CONCLUSIONS: Importantly, half of the PD patients had an inadequate heart rate increase during submaximal exercise, which was likely caused by cardiac sympathetic denervation leading to autonomic dysfunction. PD patients should therefore be screened to identify their limitations in exercise performance. Caution should be applied when prescribing beta blockers, as they might limit physical activities further.

Contains fulltext : 97020.pdf (Publisher’s version ) (Closed access) OBJECTIVE: : To estimate whether normotensive women who were born small for gestational age have low plasma volume in adult life, which is associated with later chronic hypertension. METHODS: : In 280 normotensive women with a history of hypertension in pregnancy, we recorded recalled gestational age and weight at birth and measured plasma volume (I-human serum albumin indicator dilution method). To correct for possible confounders, we recorded recent obstetric history and measured in each individual all constituents of the metabolic syndrome (World Health Organization criteria), sex hormones (progesterone and estradiol), renal function, and cardiac performance at rest (echocardiography). We estimated daily activity level with a validated questionnaire (Short Questionnaire to Assess Health-enhancing physical activity). We studied the relation between women's own birth weight centile and her adult plasma volume (mL) and adjusted for the effects of confounding variables using multiple linear regression analysis. RESULTS: : Birth weight correlated positively with adult plasma volume (P

Contains fulltext : 98070.pdf (Publisher’s version ) (Closed access) The pathophysiology of orthostatic hypotension in Parkinson's disease (PD) is incompletely understood. The primary focus has thus far been on failure of the baroreflex, a central mediated vasoconstrictor mechanism. Here, we test the role of two other possible factors: 1) a reduced peripheral vasoconstriction (which may contribute because PD includes a generalized sympathetic denervation); and 2) an inadequate plasma volume (which may explain why plasma volume expansion can manage orthostatic hypotension in PD). We included 11 PD patients with orthostatic hypotension (PD + OH), 14 PD patients without orthostatic hypotension (PD - OH), and 15 age-matched healthy controls. Leg blood flow was examined using duplex ultrasound during 60 degrees head-up tilt. Leg vascular resistance was calculated as the arterial-venous pressure gradient divided by blood flow. In a subset of 9 PD + OH, 9 PD - OH, and 8 controls, plasma volume was determined by indicator dilution method with radiolabeled albumin ((125)I-HSA). The basal leg vascular resistance was significantly lower in PD + OH (0.7 +/- 0.3 mmHg.ml(-1).min) compared with PD - OH (1.3 +/- 0.6 mmHg.ml(-1).min, P < 0.01) and controls (1.3 +/- 0.5 mmHg.ml(-1).min, P < 0.01). Leg vascular resistance increased significantly during 60 degrees head-up tilt with no significant difference between the groups. Plasma volume was significantly larger in PD + OH (3,869 +/- 265 ml) compared with PD - OH (3,123 +/- 377 ml, P < 0.01) and controls (3,204 +/- 537 ml, P < 0.01). These results indicate that PD + OH have a lower basal leg vascular resistance in combination with a larger plasma volume compared with PD - OH and controls. Despite the increase in leg vascular resistance during 60 degrees head-up tilt, PD + OH are unable to maintain their blood pressure.

Item does not contain fulltext Regional heterogeneity in wall architecture and thickness may be present between conduit arteries in the upper and lower limbs in humans. These differences in wall architecture may, in turn, influence vascular responsiveness. Folkow proposed in the 1950s that heterogeneity in wall-to-lumen ratio (W:L) could contribute to differences in vascular responsiveness, but this hypothesis has never been directly confirmed in vivo. Our first aim was to examine wall thickness and W:L across arteries in the lower (common and superficial femoral) and upper limbs (brachial and radial) of healthy men (n=35) using high resolution ultrasound. In a subgroup (n=20) we examined the relationship between W:L of these arteries, physiological (flow-mediated dilation, FMD) and pharmacological vasodilation (glyceryl trinitrate, GTN). Diameter and wall thickness differed significantly across all arteries (ANOVA P

Brachial artery flow-mediated dilation (FMD) is a strong predictor of future cardiovascular disease and is believed to represent a “barometer” of systemic endothelial health. Although a recent study [Padilla et al. Exp Biol Med (Maywood) 235: 1287–1291, 2010] in pigs confirmed a strong correlation between brachial and femoral artery endothelial function, it is unclear to what extent brachial artery FMD represents a systemic index of endothelial function in humans. We conducted a retrospective analysis of data from our laboratory to evaluate relationships between the upper (i.e., brachial artery) vs. lower limb (superficial femoral n = 75; popliteal artery n = 32) endothelium-dependent FMD and endothelium-independent glyceryl trinitrate (GTN)-mediated dilation in young, healthy individuals. We also examined the relationship between FMD assessed in both brachial arteries ( n = 42). There was no correlation between brachial and superficial femoral artery FMD ( r2= 0.008; P = 0.46) or between brachial and popliteal artery FMD ( r2= 0.003; P = 0.78). However, a correlation was observed in FMD between both brachial arteries ( r2= 0.34; P < 0.001). Brachial and superficial femoral artery GTN were modestly correlated ( r2= 0.13; P = 0.007), but brachial and popliteal artery GTN responses were not ( r2= 0.08; P = 0.11). Collectively, these data indicate that conduit artery vasodilator function in the upper limbs (of healthy humans) is not predictive of that in the lower limbs, whereas measurement of FMD in one arm appears to be predictive of FMD in the other. These data do not support the hypothesis that brachial artery FMD in healthy humans represents a systemic index of endothelial function.

Item does not contain fulltext We measured changes in maximal voluntary and electrically evoked torque and rate of torque development because of limb unloading. We investigated whether these changes during single joint isometric muscle contractions were related to changes in jump performance involving dynamic muscle contractions and several joints. Six healthy male subjects (21 +/- 1 years) underwent 3 weeks of unilateral lower limb suspension (ULLS) of the right limb. Plantar flexor and knee extensor maximal voluntary contraction (MVC) torque and maximal rate of torque development (MRTD), voluntary activation, and maximal triplet torque (thigh; 3 pulses at 300 Hz) were measured next to squat jump height before and after ULLS. MVC of plantar flexors and knee extensors (MVCke) and triplet torque decreased by 12% (P = 0.012), 21% (P = 0.001) and 11% (P = 0.016), respectively. Voluntary activation did not change (P = 0.192). Absolute MRTD during voluntary contractions decreased for plantar flexors (by 17%, P = 0.027) but not for knee extensors (P = 0.154). Absolute triplet MRTD decreased by 17% (P = 0.048). The reduction in MRTD disappeared following normalization to MVC. Jump height with the previously unloaded leg decreased significantly by 28%. No significant relationships were found between any muscle variable and jump height (r < 0.48), but decreases in torque were (triplet, r = 0.83, P = 0.04) or tended to be (MVCke r = 0.71, P = 0.11) related to decreases in jump height. Thus, reductions in isometric muscle torque following 3 weeks of limb unloading were significantly related to decreases in the more complex jump task, although torque in itself (without intervention) was not related to jump performance. 01 januari 2012

Maintaining blood pressure during orthostatic challenges is primarily achieved by baroreceptor-mediated activation of the sympathetic nervous system, which can be divided into preganglionic and postganglionic parts. Despite their preganglionic autonomic failure, spinal cord-injured individuals demonstrate a preserved peripheral vasoconstriction during orthostatic challenges. Whether this also applies to patients with postganglionic autonomic failure is unknown. Therefore, we assessed leg vasoconstriction during 60° head-up tilt in five patients with pure autonomic failure (PAF) and two patients with autonomic failure due to dopamine-β-hydroxylase (DBH) deficiency. Ten healthy subjects served as controls. Leg blood flow was measured using duplex ultrasound in the right superficial femoral artery. Leg vascular resistance was calculated as the arterial-venous pressure gradient divided by blood flow. DBH-deficient patients were tested off and on the norepinephrine pro-drug l-threo-dihydroxyphenylserine (l-DOPS). During 60° head-up tilt, leg vascular resistance increased significantly in PAF patients [0.40 ± 0.38 (+30%) mmHg·ml−1·min−1]. The increase in leg vascular resistance was not significantly different from controls [0.88 ± 1.04 (+72%) mmHg·ml−1·min−1]. In DBH-deficient patients, leg vascular resistance increased by 0.49 ± 0.01 (+153%) and 1.52 ± 1.47 (+234%) mmHg·ml−1·min−1 off and on l-DOPS, respectively. Despite the increase in leg vascular resistance, orthostatic hypotension was present in PAF and DBH-deficient patients. Our results demonstrate that leg vasoconstriction during orthostatic challenges in patients with PAF or DBH deficiency is not abolished. This indicates that the sympathetic nervous system is not the sole or pivotal mechanism inducing leg vasoconstriction during orthostatic challenges. Additional vasoconstrictor mechanisms may compensate for the loss in sympathetic nervous system control.

Background: Prolonged, moderate-intensity exercise training is routinely prescribed to subjects with obesity. In the general population, this type of exercise can lead to fluid and sodium imbalance. However, little is known whether obesity alters the risk of fluid and sodium imbalances. Objective: This study examined physiological responses, such as core body temperature, fluid and sodium balance, in lean (BMIo25), overweight (25oBMIo30) and obese (BMI430) subjects during prolonged moderate-intensity exercise. Subjects: A total of 93 volunteers (24–80 years), stratified for BMI, participated in the Nijmegen Marches and walked 30–50km at a self-selected pace. Heart rate and core body temperature were recorded every 5km. Subjects reported fluid intake, while urine output was measured and sweat rate was calculated. Baseline and post-exercise plasma sodium levels were determined, and urinary specific gravity levels were assessed before and after exercise. Results: BMI groups did not differ in training status preceding the experiment. Exercise duration (8h 41±1h 36min) and intensity (72±9% HRmax) were comparable across groups, whereas obese subjects tended to have a higher maximum core body temperature than lean controls (P ¼0.06). Obese subjects demonstrated a significantly higher fluid intake (Po0.001) and sweat rate (Po0.001), but lower urine output (Po0.05) compared with lean subjects. In addition, higher urine specific gravity levels were observed in obese versus lean subjects after exercise (Po0.05). Furthermore, plasma-sodium concentration did not change in lean subjects after exercise, whereas plasma-sodium levels increased significantly (Po0.001) in overweight and obese subjects. Also, overweight and obese subjects demonstrated a significantly larger decrease in body mass after exercise than lean controls (Po0.05). Conclusion: Obese subjects demonstrate a larger deviation in markers of fluid and sodium balance than their lean counterparts during prolonged moderate-intensity exercise. These findings suggest that overweight and obese subjects, especially under strenuous environmental conditions, have an increased risk to develop fluid and sodium imbalances. International Journal of Obesity advance online publication, 25 January 2011; doi:10.1038/ijo.2010.277

Item does not contain fulltext Individuals with a spinal cord injury (SCI) have compromised afferent and efferent information below the lesion. Intact afferent information regarding skin temperature and the ability to regulate skin blood flow lead to an altered heat balance, which may impact the circadian variation in core body temperature (Tcore) and sleep-wake cycle. The authors assessed the circadian variation of Tcore in SCI individuals and able-bodied controls matched for the timing of the sleep-wake cycle. The authors examined subjects who had a high (cervical) or a low (thoracic) lesion. Intestinal Tcore (telemetry system) and physical activity (ambulatory activity monitor) levels were measured continuously and simultaneously in 8 tetraplegics, 7 paraplegics, and 8 able-bodied controls during one 24-h period of "normal" living. The regression slope between activity and Tcore was also calculated for each 2-h bin. Circadian rhythm parameters were estimated with partial Fourier time-series analysis, and groups were compared with general linear models, adjusted for the influence of individual wake-time. The (mean +/- SD) dominant period length for controls, paraplegics, and tetraplegics were 24.4 +/- 5.4 h, 22.5 +/- 5.0 h, and 16.5 +/- 5.1 h, respectively (p = .02). A significantly more pronounced 8-h harmonic was found for the variation in Tcore of SCI individuals (p = .05). Tetraplegics showed the highest nocturnal mean Tcore (p = .005), a 5-h phase-advanced circadian trough time (p = .04), and more variable relationships between physical activity and Tcore (p = .03). Taken together, tetraplegics demonstrate a pronounced disturbance of the circadian variation of Tcore, whereas the variation of Tcore in paraplegics was comparable to able-bodied controls.

Exercise training is an important adjunct to medical therapy in chronic heart failure, but the extent to which exercise impacts on conduit artery remodeling is unknown. The aim of this study was to evaluate the impact of aerobic and resistance exercise training modalities on arterial remodeling in patients with chronic heart failure. We randomized 36 untrained subjects with chronic heart failure to resistance training (58.8±3.5 years), aerobic training (61.3±2.8 years), or an untrained control group (64.4±2.4 years). Peak oxygen consumption during cycle ergometry increased after 12 weeks in both the resistance and aerobic training ( P P P P P P

Item does not contain fulltext Beneficial effects of exercise training on the vasculature have been consistently reported in subjects with cardiovascular risk factors or disease, whereas studies in apparently healthy subjects have been less uniform. In this review, we examine evidence pertaining to the impact of exercise training on conduit and resistance vessel function and structure in asymptomatic subjects. Studies of arterial function in vivo have mainly focused on the endothelial nitric oxide dilator system, which has generally been shown to improve following training. Some evidence suggests that the magnitude of benefit depends upon the intensity or volume of training and the relative impact of exercise on upregulation of dilator pathways versus effects of inflammation and/or oxidation. Favourable effects of training on autonomic balance, baroreflex function and brainstem modulation of sympathetic control have been reported, but there is also evidence that basal vasoconstrictor tone increases as a result of training such that improvements in intrinsic vasodilator function and arterial remodelling are counterbalanced at rest. Studies of compliance suggest increases in both the arterial and the venous sides of the circulation, particularly in older subjects. In terms of mechanisms, shear stress appears to be a key signal to improvement in vascular function, whilst increases in pulse pressure and associated haemodynamics during bouts of exercise may transduce vascular adaptation, even in vascular beds which are distant from the active muscle. Different exercise modalities are associated with idiosyncratic patterns of blood flow and shear stress, and this may have some impact on the magnitude of exercise training effects on arterial function and remodelling. Other studies support the theory that that there may be different time course effects of training on specific vasodilator and constrictor pathways. A new era of understanding of the direct impacts of exercise and training on the vasculature is evolving, and future studies will benefit greatly from technological advances which allow direct characterization of arterial function and structure.

Item does not contain fulltext Motor-impaired individuals such as tetraplegics could benefit from Brain-Computer Interfaces with an intuitive control mechanism, for instance for the control of a neuroprosthesis. Whereas BCI studies in healthy users commonly focus on motor imagery, for the eventual target users, namely patients, attempted movements could potentially be a more promising alternative. In the current study, EEG frequency information was used for classification of both imagined and attempted movements in tetraplegics. Although overall classification rates were considerably lower for tetraplegics than for the control group, both imagined and attempted movement were detectable. Classification rates were significantly higher for the attempted movement condition, with a mean rate of 77%. These results suggest that attempted movement is an appropriate task for BCI control in long-term paralysis patients. 3 p.

Item does not contain fulltext Aging leads to accumulation of irreversible advanced glycation end-products (AGEs), contributing to vascular stiffening and endothelial dysfunction. When combined with the AGE-crosslink breaker Alagebrium, exercise training reverses cardiovascular aging in experimental animals. This study is the first to examine the effect of Alagebrium, with and without exercise training, on endothelial function, arterial stiffness and cardiovascular risk in older individuals. Forty-eight non-exercising individuals (mean age 70 +/- 4 years) without manifest diseases or use of medication were allocated into 4 groups for a 1-year intervention: Exercise training & Alagebrium (200 mg/day); exercise training & placebo; no exercise training & Alagebrium (200 mg/day); and no exercise training & placebo. We performed a maximal exercise test (VO2max) and measured endothelial function using venous occlusion plethysmography and intra-arterial infusion of acetylcholine, sodium nitroprusside and NG-monomethyl-l-arginine. Arterial stiffness was measured using pulse wave velocity. Cardiovascular risk was calculated using the Lifetime Risk Score (LRS). In the exercise training groups, LRS and VO2max improved significantly (23.9 +/- 4.5 to 27.2 +/- 4.6mLO2/min/kg, p < 0.001). Endothelial response to the vasoactive substances did not change, nor did arterial stiffness in any of the four groups. In conclusion, one year of exercise training significantly improved physical fitness and lifetime risk for cardiovascular disease without affecting endothelial function or arterial stiffness. The use of the AGE-crosslink breaker Alagebrium had no independent effect on vascular function, nor did it potentiate the effect of exercise training. Despite the clinical benefits of exercise training for older individuals, neither exercise training nor Alagebrium (alone or in combination) was able to reverse the vascular effects of decades of sedentary aging. 01 december 2013

Objective: To describe changes in pulmonary function (PF) during the 5 years after inpatient rehabilitation in persons with spinal cord injury (SCI) and to study potential determinants of change.Design: Prospective cohort study.Setting: Eight rehabilitation centers with specialized SCI units.Participants: Persons with SCI (N=180).Interventions: Not applicable.Main Outcome Measures: PF was determined by forced vital capacity (PVC) and forced expiratory volume in 1 second (FEV1) as a percentage of the predicted value, at the start of rehabilitation, at discharge, and 1 and 5 years after discharge from inpatient rehabilitation. The population was divided into 3 subgroups on the basis of whether their PF declined, stabilized, or improved.Results: PVC improved on average 5.1% over the whole period between discharge of inpatient rehabilitation and 5 years thereafter, but changes differed largely between persons. PVC declined in 14.9% of the population during the first year after discharge. During this year, body mass index, inspiratory muscle strength, change in peak power output, and change in peak oxygen uptake differed significantly between subgroups. PVC declined in 28.3% of the population during the following 4 years, but no differences were found between the subgroups for this period. Subgroups based on changes in FEV1 differed only with respect to change in peak oxygen uptake the first year after discharge.Conclusions: In our study, many persons with SCI showed a decline in PF, larger than the normal age-related decline, during the 5 years after inpatient rehabilitation. Results suggest that a decline in PF during the first year after inpatient rehabilitation is associated with higher body mass index, lower inspiratory muscle strength, and declined physical fitness. Archives of Physical Medicine and Rehabilitation 2013;94:1540-6 (C) 2013 by the American Congress of Rehabilitation Medicine

Contains fulltext : 118187.pdf (Publisher’s version ) (Open Access) OBJECTIVE: To compare the effects of inspiratory resistance training and isocapnic hyperpnoea vs incentive spirometry (placebo) on respiratory function, voice, thorax mobility and quality of life in individuals with tetraplegia. DESIGN: Randomized controlled trial. PATIENTS/METHODS: A total of 24 individuals with traumatic, complete tetraplegia (C5-C8, American Spinal Injury Association (ASIA) Impairment Scale; AIS A) were randomly assigned to 1 of 3 groups. They completed 32 supervised training sessions over a period of 8 weeks. Before and after the training period, the following tests were performed: body plethysmography, inspiratory and expiratory muscle strength, subjective breathing parameters using a visual analogue scale, voice measurements, thorax mobility and quality of life. Cohen's effect sizes and Kruskal-Wallis tests for differences between pre- and post-training values were calculated. RESULTS: Compared with placebo training, inspiratory resistance training showed high effect sizes for inspiratory muscle strength (d = 1.13), the subjective ability "to blow one's nose" (d = 0.97) and the physical component of quality of life (d = 0.82). Isocapnic hyperpnoea compared with placebo showed a high effect size for breathlessness during exercise (d = 0.81). We found a significant effect of inspiratory resistance training vs placebo (p = 0.016) and vs isocapnic hyperpnoea (p = 0.012) for inspiratory muscle strength. CONCLUSION: In individuals with motor and sensory complete tetraplegia during the first year post-injury, inspiratory resistance training is more advantageous than isocapnic hyperpnoea, performed 4 times a week for 10 min.

Item does not contain fulltext BACKGROUND: Impaired brachial artery endothelial function, assessed by flow-mediated dilation (FMD), provides a strong prognostic index of cardiovascular events in asymptomatic adults and those with cardiovascular disease. However, the relationship between FMD and carotid intima-medial thickness (cIMT) in young people is unknown. We hypothesized that impaired FMD, and decreased FMD over time, would predict cIMT. DESIGN AND METHODS: FMD and cIMT were assessed using high-resolution Doppler ultrasound in 53 children (18 boys) aged 10.3 +/- 0.3 years. FMD was assessed at baseline and 4-month and 30-month follow up. cIMT was assessed at 30-months. RESULTS: There was no significant relationship between FMD measured at baseline (10.7 +/- 4.3) and cIMT at 30 months. FMD was depressed at 4 months (7.2 +/- 3.5, p < 0.05) and 30 months (8.2 +/- 3.3, p = 0.51). However, there was no correlation between changes in FMD and cIMT. CONCLUSION: Changes in arterial function occurred in young subjects across a 30-month time frame; however, these changes were unrelated to individual differences in cIMT in this cohort. These data contrast with findings in adults and indicate that longer periods of functional impairment may be necessary before atherosclerotic wall thickening becomes apparent in young people, suggesting there is a 'window of opportunity' for preventative intervention strategies. 01 oktober 2013

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Item does not contain fulltext Reperfusion is mandatory after ischemia but also triggers ischemia-reperfusion (I/R) injury. Ischemic preconditioning (IPC) can limit endothelial I/R injury. Nonetheless, translation of IPC to the clinical arena is often disappointing. Since application of IPC typically relates to older patients, efficacy of IPC may be attenuated with aging. Our objective was to examine the impact of advanced age on the ability of IPC to protect against endothelial dysfunction due to I/R injury. We included 15 healthy young (20-25 yr) and 15 older (68-77 yr) men. We examined brachial artery endothelial function using flow-mediated dilation (FMD) before and after arm I/R (induced by inflation of an upper-arm blood pressure cuff for 20 min and 15 min of reperfusion). In a randomized order, I/R was preceded by IPC or a control intervention consisting of three cycles of 5 min upper-arm cuff inflation to 220 or 20 mmHg, respectively. As a result, in young men, FMD decreased significantly after I/R (6.4 +/- 2.7 to 4.4 +/- 2.5%). This decrease was not present when I/R was preceded by IPC (5.9 +/- 2.3 to 5.6 +/- 2.5%). IPC-induced protection appeared to be significantly reduced in the elderly patients (P = 0.04). Although FMD decreased after I/R in older men (3.5 +/- 1.7 to 2.5 +/- 1.0%), IPC could not prevent this (3.7 +/- 2.1 to 2.2 +/- 1.1%). In conclusion, this study is the first to observe in humans in vivo that older age is associated with an abolished effect of IPC to protect against endothelial dysfunction after I/R in the brachial artery. This provides a possible explanation for the problematic translation of strategies that reduce I/R injury from preclinical work to the clinical arena.

Contains fulltext : 119217.pdf (Publisher’s version ) (Closed access) The metabolic syndrome, a combination of interrelated metabolic risk factors, is associated with insulin resistance and promotes the development of cardiovascular diseases and type 2 diabetes mellitus. There is a close link between inflammation and metabolic disease, but the responsible mechanisms remain elusive. The aim of this study was to identify differentially expressed genes in insulin-resistant skeletal muscle tissue of women with the metabolic syndrome compared with healthy control women. Women with the metabolic syndrome (n = 19) and healthy control women (n = 20) were extensively phenotyped, insulin sensitivity was measured using a hyperinsulinaemic euglycaemic clamp, and a skeletal muscle biopsy was obtained. Gene expression levels were compared between the two groups by microarrays. The upregulated genes in skeletal muscle of the women with the metabolic syndrome were primarily enriched for inflammatory response-associated genes. The three most significantly upregulated of this group, interleukin 6 receptor (IL6R), histone deacetylase 9 (HDAC9) and CD97 molecule (CD97), were significantly correlated with insulin resistance. Taken together, these findings suggest an important role for a number of inflammatory-related genes in the development of skeletal muscle insulin resistance.

Item does not contain fulltext OBJECTIVE: To investigate walking ability and quality of life of osseointegrated leg prostheses compared with socket prostheses. DESIGN: Prospective case-control study. SETTING: University medical center. PARTICIPANTS: Subjects (N=22) with transfemoral amputation (1 bilateral) referred to our center because of socket-related skin and residual limb problems resulting in limited prosthesis use. Their mean age was 46.5 years (range, 23-67y) and mean time since amputation was 16.4 years (range, 2-45y). Causes of amputation were trauma (n=20) and tumor (n=2). INTERVENTION: Implantation of an osseointegration prosthesis (OIP). MAIN OUTCOME MEASURES: Global score of the Questionnaire for Persons With a Transfemoral Amputation (Q-TFA), prosthesis use, 6-minute walk test (6MWT), Timed Up & Go (TUG) test, and oxygen consumption during treadmill walking. RESULTS: With the socket prosthesis, the mean +/- SD Q-TFA global score, prosthesis use, 6MWT, TUG, and oxygen consumption were 39+/-4.7 points, 56+/-7.9h/wk, 321+/-28m, 15.1+/-2.1 seconds, and 1330+/-310mL/min, respectively, and significantly improved with OIP to 63+/-5.3 points, 101+/-2.4h/wk, 423+/-21m, 8.1+/-0.7 seconds, and 1093+/-361mL/min, respectively. CONCLUSIONS: Osseointegration is a suitable intervention for persons whose prosthesis use is reduced because of socket-related problems. Subjects with OIP significantly increased their walking ability and prosthesis-related quality of life.

VERDIJK, L. B., M. L. DIRKS, T. SNIJDERS, J. J. PROMPERS, M. BEELEN, R. A. M. JONKERS, D. H. J. THIJSSEN, M. T. E. HOPMAN, and L. J. C. VAN LOON. Reduced Satellite Cell Numbers with Spinal Cord Injury and Aging in Humans. Med. Sci. Sports Exerc., Vol. 44, No. 12, pp. 2322–2330, 2012. Introduction: Both sarcopenia and spinal cord injury (SCI) are characterized by the loss of skeletal muscle mass and function. Despite obvious similarities in atrophy between both models, differences in muscle fiber size and satellite cell content may exist on a muscle fiber type–specific level. Methods: In the present study, we compared skeletal muscle fiber characteristics between wheelchair-dependent young males with SCI (n = 8, 32 T 4 yr), healthy elderly males (n = 8, 75 T 2 yr), and young controls (n = 8, 31 T 3 yr). Muscle biopsies were collected to determine skeletal muscle fiber type composition, fiber size, and satellite cell content. Results: Severe atrophy and a shift toward approximately 90% Type II muscle fibers were observed in muscle obtained from males with SCI. Muscle fiber size was substantially smaller in both the SCI (Types I and II fibers) and elderly subjects (Type II fibers) when compared with the controls. Satellite cell content was substantially lower in the wheelchair-dependent SCI subjects in both the Types I and II muscle fibers (0.049 T 0.019 and 0.050 T 0.005 satellite cells per fiber, respectively) when compared with the young controls (0.104 T 0.011 and 0.117 T 0.009 satellite cells per fiber, respectively). In the elderly, the number of satellite cells was lower in the Type II muscle fibers only (0.042 T 0.005 vs 0.117 T 0.009 satellite cells per fiber in the elderly vs young controls, respectively). Conclusion: This is the first study to show that muscle fiber atrophy as observed with SCI (Types I and II fibers) and aging (Type II fibers) is accompanied by a muscle fiber type–specific reduction in satellite cell content in humans. Key Words: PARAPLEGIA, SARCOPENIA, SKELETAL MUSCLE STEM CELLS, FIBER TYPE SPECIFIC

Background: Physical activity is known to influence sleep efficiency. Relatively little is known about the relationship between physical activity and sleep efficiency in young and older humans and the impact of exercise training on sleep efficiency in healthy older individuals. Objectives: To determine the relationship between physical fitness and daily energy expenditure with sleep efficiency in young and older subjects, and assess the effect of 12-month exercise training on sleep efficiency in healthy older participants. Methods: The relationship between physical fitness (maximal cycling test) and daily energy expenditure (accelerometry) with sleep efficiency (accelerometry) was examined cross-sectionally in 12 healthy young adults (27 ± 5 years) and 21 healthy older participants (69 ± 3 years). Subsequently, the effect of 12-month exercise training (n = 11) or control period (n = 10) on sleep efficiency in older participants was examined using a randomized controlled trial. Results: Daily energy expenditure and sleep efficiency did not differ between young and older subjects. A significant correlation was found between energy expenditure and sleep efficiency (r = 0.627, p = 0.029) in young adults, but not in older participants (r = –0.158, p = 0.49). Physical fitness did not correlate with sleep efficiency in either group. Exercise training significantly improved physical fitness (15.0%, p < 0.001), but failed to alter sleep characteristics such as sleep efficiency, sleep onset latency and awakenings. Conclusions: We found that young adults with higher daily energy expenditure have greater sleep efficiency, whilst this relationship is diminished with advanced age. In contrast, we found no correlation between physical fitness and sleep characteristics in healthy young or older participants, which may explain the lack of improvement in sleep characteristics in older participants with 12-month exercise training. Exercise training may be more successful in subjects with existing sleep disturbances to improve sleep characteristics rather than in healthy older subjects.

Patiënten met RSI hebben niet alleen problemen in de aangedane arm. Ook in de arm zonder klachten zijn spierdoorbloeding, zuurstofopname en vaatfunctie sterk verminderd. Dat concludeert promovendus Jaap Brunnekreef. Verder blijkt dat de spierkarakteristieken van patiënten met RSI-klachten anders zijn dan van gezonde vrijwilligers. Zo kenmerkt het spierweefsel van RSI-patiënten zich door een snellere vermoeidheid. De behandeling van RSI moet hierdoor breder van opzet zijn dan alleen het lokaal behandelen van de klachten, stelt Brunnekreef.

Item does not contain fulltext OBJECTIVE: In this case study, we describe the effects of a particular individual's concentration/meditation technique on autonomic nervous system activity and the innate immune response. The study participant holds several world records with regard to tolerating extreme cold and claims that he can influence his autonomic nervous system and thereby his innate immune response. METHODS: The individual's ex vivo cytokine response (stimulation of peripheral blood mononuclear cells with lipopolysaccharide [LPS]) was determined before and after an 80-minute full-body ice immersion during which the individual practiced his concentration/meditation technique. Furthermore, the individual's in vivo innate immune response was studied while practicing his concentration/mediation technique during human endotoxemia (intravenous administration of 2 ng/kg LPS). The results from the endotoxemia experiment were compared with a historical cohort of 112 individuals who participated in endotoxemia experiments in our institution. RESULTS: The ex vivo proinflammatory and anti-inflammatory cytokine response was greatly attenuated by concentration/meditation during ice immersion, accompanied by high levels of cortisol. In the endotoxemia experiment, concentration/meditation resulted in increased circulating concentrations of catecholamines, and plasma cortisol concentrations were higher than in any of the previously studied participants. The individual's in vivo cytokine response and clinical symptoms after LPS administration were remarkably low compared with previously studied participants. CONCLUSIONS: The concentration/meditation technique used by this particular individual seems to evoke a controlled stress response. This response is characterized by sympathetic nervous system activation and subsequent catecholamine/cortisol release, which seems to attenuate the innate immune response. 01 juni 2012

Item does not contain fulltext PURPOSE: This study aimed to investigate localized and systemic effects of chronic exercise and inactivity on conduit artery remodeling in humans. METHODS: We recruited elite athletes engaged in predominantly lower limb (LL runners/cyclists, n = 10) or upper limb (UL canoe paddlers, n = 12) exercise and matched able-bodied, recreationally active, controls (C, n = 16). We also studied wheelchair controls (spinal cord injury, n = 9) and athletes (spinal cord injury, n = 1; spina bifida, n = 4). Carotid, brachial, and superficial femoral (SF) artery diameter and wall thickness were assessed using high-resolution ultrasound. RESULTS: Brachial diameters were significantly larger in UL and wheelchair users (athletes and controls) compared with C (both P < 0.05). SF artery diameter in wheelchair controls was significantly smaller compared with the other groups, with LL athletes having significantly greater lumen diameter than controls (both P < 0.05). In all arteries, a lower wall thickness was found in able-bodied athletes compared with C, including wheelchair athletes compared with wheelchair controls (P < 0.001). In the SF artery, wall-to-lumen-ratio was significantly lower in able-bodied athletes and higher in wheelchair controls compared with able-bodied controls (P < 0.001). In the brachial and carotid arteries, able-bodied and wheelchair athletes demonstrated lower wall-to-lumen-ratio than less active wheelchair controls and able-bodied controls (P < 0.001). CONCLUSIONS: These findings suggest that remodeling of the arterial wall occurs systemically in response to exercise training and is unrelated to exercise type in humans. Conversely, localized effects are evident with respect to the effect of exercise on arterial diameter. These findings have implications for our understanding of the effects of exercise on arterial structure and function in humans. 01 mei 2012

Background— Radial artery catheterization is associated with endothelial denudation and impaired vasodilator function, while postcatheterization exercise training may enhance artery function. The impact of catheterization and subsequent exercise training on low-flow mediated vasoconstriction (L-FMC) has not previously been studied. The aim of this study was to examine whether radial artery L-FMC is impaired by catheterization and consequent endothelial denudation. A further aim was to examine the effect of local handgrip exercise training on radial artery L-FMC and flow-mediated dilation (FMD) after transradial catheterization. Methods and Results— Thirty-two subjects undergoing transradial catheterization underwent assessment of L-FMC and FMD in the catheterized and contralateral radial artery before, and the day after, catheterization. A further 18 patients were recruited and randomly assigned to either a 6-week handgrip exercise training program (N=9) or a nonexercise control period (N=9). L-FMC was attenuated 1 day postcatheterization in the catheterized arm (−2.07±0.84 to 0.35±0.83), but unchanged in the noncatheterized arm (−0.93±0.86 to −0.90±0.92; P P =0.06; L-FMC-pre, −3.26±1.19; L-FMC-post, −1.34±1.27%; P Conclusions— Catheterization, and associated endothelial denudation, decreases L-FMC in the radial artery, suggesting that it is endothelium-dependent. Moreover, we demonstrate for the first time that exercise training has beneficial impacts on radial artery vasodilator and constrictor function.

Item does not contain fulltext Physical inactivity in response to a spinal cord injury (SCI) represents a potent stimulus for conduit artery remodelling. Changes in conduit artery characteristics may be induced by the local effects of denervation (and consequent extreme inactivity below the level of the lesion), and also by systemic adaptations due to whole body inactivity. Therefore, we assessed the time course of carotid (i.e. above lesion) and common femoral artery (i.e. below lesion) lumen diameter and wall thickness across the first 24 weeks after an SCI. Eight male subjects (mean age 35 +/- 14 years) with a traumatic motor complete spinal cord lesion between T5 and L1 (i.e. paraplegia) were included. Four subjects were measured across the first 6 weeks after SCI, whilst another four subjects were measured from 8 until 24 weeks after SCI. Ultrasound was used to examine the diameter and wall thickness from the carotid and common femoral arteries. Carotid artery diameter did not change across 24 weeks, whilst femoral artery diameter stabilised after the rapid initial decrease during the first 3 weeks after the SCI. Carotid and femoral artery wall thickness showed no change during the first few weeks, but increased both between 6 and 24 weeks (P < 0.05). In conclusion, SCI leads to a rapid and localised decrease in conduit artery diameter which is isolated to the denervated and paralyzed region, whilst wall thickness gradually increases both above and below the lesion. This distinct time course of change in conduit arterial diameter and wall thickness suggests that distinct mechanisms may contribute to these adaptations.

Item does not contain fulltext Thickening of the carotid artery wall has been adopted as a surrogate marker of pre-clinical atherosclerosis, which is strongly related to increased cardiovascular risk. The cardioprotective effects of exercise training, including direct effects on vascular function and lumen dimension, have been consistently reported in asymptomatic subjects and those with cardiovascular risk factors and diseases. In the present review, we summarize evidence pertaining to the impact of exercise and physical activity on arterial wall remodelling of the carotid artery and peripheral arteries in the upper and lower limbs. We consider the potential role of exercise intensity, duration and modality in the context of putative mechanisms involved in wall remodelling, including haemodynamic forces. Finally, we discuss the impact of exercise training in terms of primary prevention of wall thickening in healthy subjects and remodelling of arteries in subjects with existing cardiovascular disease and risk factors. 01 april 2012

Item does not contain fulltext Repetitive Strain Injury (RSI) is a disabling upper extremity overuse injury that may be associated with pathophysiological changes in the vasculature. In this study we investigated whether RSI is associated with endothelial dysfunction and impaired exercise-induced blood flow in the affected forearm. 10 patients with RSI (age, 40.2 +/- 10.3; BMI, 23.8 +/- 3.3) and 10 gender- and age-matched control subjects (age, 38.0 +/- 12.4; BMI, 22.7 +/- 3.4) participated in this study. Brachial artery blood flow was measured at rest and during 3-min periods of isometric handgrip exercise at 15%, 30% and 45% of the individual maximal voluntary contraction. Brachial artery endothelial function was assessed as the flow mediated dilation (FMD), by measuring brachial artery diameter and velocity before and after 5-min ischemic occlusion. We found a lower exercise-induced brachial artery blood flow in patients with RSI than in controls (p=0.04). Brachial artery FMD was significantly lower in patients with RSI than in controls (p

Contains fulltext : 110649.pdf (Publisher’s version ) (Closed access) Individuals with a spinal cord injury (SCI), especially with tetraplegia, experience poor sleep quality, and this may be related to impaired control of circadian rhythmicity. Here, we examined the evening onset of melatonin secretion, an important hormone for the initiation of sleep, in people with a complete cervical (tetraplegia) and thoracic (paraplegia) SCI, and age- and sex-matched able-bodied control participants. Multiple samples of salivary melatonin were obtained during the evening hours and analyzed by ELISA methods in 10 control partcipants, 9 individuals with paraplegia, and 6 individuals with tetraplegia. Sleep quality was assessed using questionnaires. Interactive effects of group and time were found for melatonin levels (P=0.022). In the control and paraplegia groups, the mean melatonin level increased significantly from 2.59 +/- 1.04 and 4.28 +/- 3.28 pg/ml at 7 PM to 10.62 +/- 4.59 and 13.10 +/- 7.39 pg/ml at 11 PM, respectively (P0.05). Decreased sleep quality was more prevalent in individuals with tetraplegia (83%) and paraplegia (75%) compared with controls (20%; P=0.02). Unlike in the control and paraplegia groups, the evening increase in melatonin concentration was completely absent in the tetraplegia group. This provides biological insight into sleep regulation in humans and provides better understanding of the poor sleep quality in people with tetraplegia. 01 juli 2012

Item does not contain fulltext OBJECTIVE: To compare the effects of inspiratory resistance training (IRT) and isocapnic hyperpnea (IH) versus incentive spirometry (placebo) on respiratory function, voice, and quality of life in individuals with motor complete tetraplegia. METHODS: In this randomized controlled trial, 24 individuals with traumatic, motor complete (AIS A) tetraplegia (C5-C8), 6 to 8 months post injury, were randomly assigned to 1 of 3 groups. They completed either 90 repetitions of IRT, 10 minutes of IH, or 16 repetitions of placebo training in 32 supervised training sessions over 8 weeks. Before and after the training period, the following tests were performed: bodyplethysmography, inspiratory and expiratory muscle strength, subjective breathing parameters using the visual analogue scale (VAS), voice measurements, and an adapted SF-12 quality of life questionnaire. A Friedman test and Cohen's effect sizes for IRT and IH versus placebo were calculated for differences between pre- and posttraining values. RESULTS: Compared to placebo training, IRT showed high effect sizes for inspiratory muscle strength (d = 1.19), VAS values of "cleaning the nose" (d = 0.99), and the physical component of subjective quality of life (d = 0.84). IH compared to placebo training showed only medium and low effect sizes. The Friedman analysis showed a significant effect for IRT versus placebo on inspiratory muscle strength (P = .030). Neither all other parameters of respiratory function nor voice measurements, subjective breathing parameters, or quality of life were significantly improved by one of the tested training methods. CONCLUSION: In individuals with motor complete tetraplegia, inspiratory muscle strength can be improved by IRT. Therefore, IRT is advantageous compared to IH for this group of patients and during the first year post injury.

Item does not contain fulltext Elevated cardiac troponin I (cTnI), a marker for cardiac damage, has been reported after high-intensity exercise in healthy subjects. Currently, little is known about the impact of prolonged moderate-intensity exercise on cTnI release, but also the impact of obesity on this response. 97 volunteers (55 men and 42 women), stratified for BMI, performed a single bout of walking exercise (30-50 km). We examined cTnI-levels before and immediately after the exercise bout in lean (BMI < 25 kg/m(2), n = 30, 57 +/- 19 years), overweight (25 /= 30 kg/m(2), n = 28, 53 +/- 9 years). Walking was performed at a self-selected pace. cTnI was assessed using a high-sensitive cTnI-assay (Centaur; clinical cut-off value >/= 0.04 mug/L). We recorded subject characteristics (body weight, blood pressure, presence of cardiovascular risk) and examined exercise intensity by recording heart rate. Mean cTnI-levels increased significantly from 0.010 +/- 0.006 to 0.024 +/- 0.046 mug/L (P < 0.001). The exercise-induced increase in cTnI was not different between lean, overweight and obese subjects (two-way ANOVA interaction; P = 0.27). In 11 participants, cTnI was elevated above the clinical cut-off value for myocardial infarction. Logistic regression analysis identified exercise intensity (P < 0.001), but not BMI, body fat percentage or waist circumference to significantly relate to positive troponin tests. In conclusion, prolonged, moderate-intensity exercise results in a comparable increase in cTnI-levels in lean, overweight and obese subjects. Therefore, measures of obesity unlikely relate to the magnitude of the post-exercise elevation in cTnI. 01 mei 2012

Contains fulltext : 109118.pdf (Publisher’s version ) (Open Access) OBJECTIVE: To develop statistical models to predict lung function and respiratory muscle strength from personal and lesion characteristics of individuals with motor complete spinal cord injury. DESIGN: Cross-sectional, multi-centre cohort study. SUBJECTS: A total of 440 individuals with traumatic, motor complete spinal cord injury, time post-injury >/= 6 months, lesion level C4-T12, underwent measurements of lung function and respiratory muscle strength. METHODS: Prediction models for lung volumes and peak inspiratory and expiratory muscle strength were calculated. Using multi-level regression models, the effects of personal characteristics (gender, age, height, body mass) and lesion characteristics (time post-injury and lesion level) were determined. RESULTS: Positive predictors of lung function parameters were: male gender, younger age, greater height, greater body mass and lower lesion level. For maximal inspiratory muscle strength, male gender, younger age, greater body mass and lower lesion level were significant positive predictors, whereas for maximal expiratory muscle strength, male gender, younger age, longer time post-injury and lower lesion level were positive influencing parameters. CONCLUSION: In contrast to predictive models for able-bodied individuals, lung function parameters of persons with spinal cord injury are influenced by body mass and lesion level. Maximal expiratory muscle strength improves with longer time post-injury. 01 juli 2012

Item does not contain fulltext BACKGROUND: Although previous studies have reported age-related wall thickening in carotid arteries, it is not clear whether this is a systemic phenomenon which is also apparent in peripheral conduit arteries or whether conduit wall thickness (WT) changes occur to a similar degree in men and women. AIM: To determine whether sex modifies the impact of ageing on WT or wall-to-lumen ratio (W:L) in atherosclerosis-prone (i.e. carotid artery, femoral, superficial femoral, popliteal artery) and atherosclerosis-resistant (i.e. brachial artery) conduit arteries. METHODS: We included 30 young (23 +/- 2 year; 15M : 15F) and 31 older (70 +/- 5 year; 18M : 13F) healthy subjects. High-resolution ultrasound was used to measure diameter, WT and wall-to-lumen ratio (W/L) in all arteries. RESULTS: Older subjects had increased WT and W/L in the carotid, femoral, superficial femoral, popliteal and brachial arteries (all P < 0.05). Compared with women, men demonstrated larger diameter and WT (both P < 0.01) across all arteries. Sex did not impact upon age-related changes in WT or W/L (P = 0.39 and 0.43 respectively). CONCLUSION: Our data suggest that age-related wall thickening, evident in the carotid artery, is also apparent in the arteries of the upper and lower limbs. The impact of age on wall thickening did not differ between men and women. These data support the presence of systemic increases in WT and W/L with age in apparently healthy humans, independent of sex.